The present invention relates to hermetic compressors, and more particularly to draining compressor oil from a hermetic compressor and recharging a hermetic compressor with oil.
In general, lubricating fluid such as oil is removed from a hermetic compressor for any number of reasons. One such reason may be that a sample of the oil is needed for testing to analyze its properties such as viscosity, for example. Additionally, it may be desired to determine the amount of oil located in the compressor housing in comparison to the amount of oil the compressor had been initially charged with, thus determining if there had been any oil loss during compressor operation. By determining the amount of oil located in the compressor housing, one can also ensure that a sufficient amount of oil is available to the compressor components during compressor operation. Further, spent oil may be removed from the compressor housing and replaced with fresh, clean, or a different type of oil.
Conventionally, to drain oil from a hermetic compressor, the compressor must be disconnected and removed from its assembly with a refrigeration system. The suction, discharge, and electrical connections are disconnected and the compressor is removed from the refrigeration system. The oil in the compressor housing is poured from the compressor housing through a drain/fill opening in the housing into a suitable container. After being drained, the compressor may be recharged with oil through the drain/fill opening and reassembled to the refrigeration system.
A problem with this method of draining oil from a hermetic compressor is that the removal of the compressor from its assembly in the refrigeration system is time consuming, labor intensive, and expensive. The removal of the compressor requires stopping refrigerant flow through the suction and discharge lines and then disconnecting the suction line, discharge line, and electrical connections. An additional problem is that refrigerant may leak from the suction and discharge lines as well as from the compressor after being disconnected.
It is desired to provide a method and apparatus for draining oil from and recharging oil into a hermetically sealed compressor without having to remove the compressor from its system.
The present invention relates to a hermetically sealed compressor having a drainage or dip tube assembly mounted in the housing thereof to facilitate draining and recharging of compressor oil. The dip tube assembly includes an elongated tube located primarily within the compressor housing having a valve, such as a Schrader valve, secured to an end thereof. The valve is mounted in the compressor housing by welding, brazing, or the like to secure the dip tube assembly therein. The tube is bent, being downwardly inclined so that the tube approaches the bottom of the compressor housing. The internal end of the tube is flattened so that the area of the opening in the end of the tube is as close to the housing bottom as possible to facilitate draining of nearly all of the compressor oil stored in the compressor housing.
The method of draining the compressor oil from the hermetically sealed compressor includes first shutting off flow to the discharge and suction lines of the compressor. The refrigerant is purged from the housing to create a vacuum therein. The housing is then charged through a service port with a gas such as dry air, nitrogen, or the like. As gas is charged into the compressor housing, the pressure inside the compressor housing increases and acts on the oil located in the sump. The pressure forces the oil into the dip tube, through the valve, and through a service hose into a container. The amount of gas charged into the compressor housing controls the pressure therein as well as the amount and speed of the oil being purged.
In order to recharge the compressor with oil, the gases are purged from the compressor housing which again creates a vacuum therein. A service hose is connected to the service port and a predetermined amount of oil is drawn through the hose into the compressor housing. The compressor is purged for a third time, creating a vacuum in the housing, and the compressor is charged with refrigerant.
Certain embodiments of the present invention provide a drainage assembly for a hermetically sealed compressor having a housing. The drainage assembly includes a drainage tube having a first and second end with a valve mounted to the first end thereof. The valve is mounted in the compressor housing with the second end of the drainage tube extending into the compressor housing. Lubricating oil is removed from the compressor housing through the drainage tube and the valve.
Certain embodiments of the present invention also provide a drainage assembly for a hermetically seal compressor having a housing with a bottom. The drainage assembly includes a drainage tube having a first and second end, the first end having a valve mounted thereon. The valve is mounted in the compressor housing. The drainage tube is downwardly inclined with the second, flattened end of the tube approaching the bottom of the compressor housing. Lubricating oil is removed from the compressor housing through the drainage tube and the valve.
Certain embodiments of the present invention also provide a method of draining oil from a hermetic compressor having a housing with a sump formed therein including shutting off refrigerant flow to a suction tube and a discharge tube mounted in the compressor housing; purging refrigerant from within the compressor housing creating a vacuum therein; charging the compressor housing with a gas through a service port mounted in the compressor housing; and forcing oil in the compressor housing to pass through a drainage assembly extending into the compressor sump and out of the compressor housing.
One advantage of the present invention is that the oil located in a hermetic compressor may be drained and recharged without having to remove the compressor from its assembly with other components of a refrigeration system.
A further advantage of the present invention is that the method used to drain and recharge hermetic compressor oil is efficient and inexpensive.